Let me explain, sorry if there was any lack of evidence. In about one thousand years Mars could be on its side, changing the deserts to ice caps. Ocean life extincts because no tides, no moon light(very important to coral reefs), currents changed by tidal tsunami. Like I said it's not really about light, its the plants and corals that really need moonlight(many plants bloom at night). If something never hit the earth and created the moon, the earth used to spin in an 8 hour day. The impacting planet hit at an angle and they believe we are so rich in iron because its core later impacted the earth and was absorbed. That explains the longer lived core and why the earth didn't turn up like Mars, or else we would have(all the heat escaping the core until it died). The faster rotation would make constant storms, much like jupiter, leading short stubby plant life and different types of animals. One small change changes the whole evolutional time line, and to me this seems like a lot of changes. There probably would have never been dinosaurs or mammals, just fish(maybe not even).